ARAMIS (Arthritis, Rheumatism, and Aging Medical Information System) is a rheumatic disease-oriented computer data bank system containing prospective longitudinal clinical data in 18 major data sets including over 44,000 patients, 443,000 patient encounters, and nearly 500,000 patient/years of follow-up. The system is represented as a distributed microprocessor oriented system with data banks resident on personal computers with augmented storage, and is accessible additionally through TYMNET or TELENET communication networks from an IBM 370-3084A computer at Stanford University. The program has two major aims: First, to continue to develop a national data resource of high-quality, longitudinal, accessible clinical data, and second, to employ these data in a systematic multi-center investigative program addressing major clinical questions in the rheumatic diseases. The program is based upon the premises that chronic diseases observation over prolonged time periods, that patient outcome results from a complex interplay of multiple factors, and that these questions need observational, in addition to experimental, study. Over 40 ARAMIS clinical investigators and epidemiologists at 14 institutions undertake over 60 projects annually. Studies in Sun City, with University of Pennsylvania graduates, and with the HANES-I follow-up program seek to identify risk factors for musculoskeletal aging. Analyses of socioeconomic factors, psychological factors, disease staging, changes in manifestations over time, and medical and surgical outcomes in rheumatoid arthritis are explored. New disease pools are established for systemic lupus erythematosus, scleroderma, myositis, fibrositis, and osteoarthritis. New data sets are established for vasculitis, Paget's Disease, and diffuse idiopathic skeletal hyperostosis (DISH). The interaction between AIDS and rheumatoid arthritis is examined. A special emphasis upon Hispanic and minority patients is included. A substantial program evaluating the side effects of anti-arthritic medications is provided. With this project, 20 years of data development at numerous institutions are brought to bear upon major clinical questions, and large, detailed, and high-quality longitudinal patient data sets are made nationally available.